There is currently a 500 Excalibur on Ebay, it's described as a 500 but my suspicion is that it is a 350 into which someone has put a 478cc engine, I am no expert so I would be happy to hear other opinions.

Hi, all 500/501 barrels have 8 fins and 350s have 6 fins. Early 501 barrels look similar to 500s but the later ones had larger and more square fins with notches for rubbers (as did the 350s); the later heads also had bigger fins. All heads have 6 fins.It should have 28mm PHBH carbs if it is a 501 (26mm for 500s).The engine looks right for a series 1 Excalibur, just make sure it's not a 350.Hope this helps

Looks like a pre Kokusan 500 motor to me (tall barrels and round slide carbs suggest it's not a 350)

However the side panels and 8500rpm redline suggest this perhaps started life as a 350, or at least has had these parts changed (in fact, excaliburs had white faced dials so the clocks are almost certainly not original)

If you do a tax check on dvla (the reg number is visible in one of the pics) it's been off the road since 2012 and is registered as a 1990 bike with a 500cc engine.

1990 definitely would have had a kokusan 501 or 350 motor so this may well be a bit of a bitsa.

But do you know what, fair play I say. Too many Excaliburs get broken for their engines and if somebody has at some point decided to put this one back together (and moreover, put a 500 motor in rather than an easier to get 350), then this bike deserves a nice home.

I hope somebody buys it and enjoys it for what it is.

(And before you think I've been on the vino, whilst I don't really like the way they look, I appreciate what they are, and it's just a shame how so many of them end up- I should know, both my dart's 501 engines came from excaliburs!)

Hi, I agree with Tom that it looks like a 'pre Kokusan 500 motor' and if not original to the bike could even be from a late 501 Camel (electric start).I've seen 3 different types of 501 barrels; fins as the 500, larger square fins with indents for rubber blocks/strips and finally large square fins with the top 3 larger again to match the head fins.As much as most of us? like the Morini mix n match possibilities it can give others grief when buying a bike especially when originality matters. Enjoy the fun

I've been asking some questions from the vendor, who seems a very helpful chap although he knows little about the bike.It appears to not have any Gillardoni markings between the fins at the base of the barrels which I thought all 501's did have, it also seems to only have a 5 speed box from going through the gears with it on the centre stand, however it does have PHBH28 carbs which would be right for a 501, my hunch would be that it's a 478cc engine with bigger carbs, but as I said before, I am no expert.